Isolation of Novacetimonas hansenii, a cellulose-producing bacterium, and its polysaccharide characterisation

The development of biomaterials using eco-friendly methodologies is an important goal for researchers. Among these materials, bacterial cellulose is produced by a non-pathogenic microorganism; has the advantages of having a three-dimensional nanofibrous structure, higher purity and crystallinity than plant cellulose; is biocompatible and biodegradable; and can be combined with other biopolymers for the development of new materials. The aim of this work was to isolate cellulose-producing bacteria from kombucha, the symbiotic culture of bacteria and yeast (SCOBY); to study the production of the biopolymer in isolated culture; and to characterize it. It was possible to isolate eight strains of acetic acid bacteria, of which two were cellulose-producing, in isolated culture. The strain with the highest polymer production was identified as Novacetimonas hansenii, which was found to be capable of producing 206 mg/l of cellulose in Y3 medium after 10 days of culture at 30°C. The isolated polymer was lyophilized and characterized by FTIR, X-ray, and SEM microscopy. The crystallinity index corresponded to 81±3 %, the evaluation of the infrared spectra was performed in the mid IR range from 500 cm–1 to 4000 cm^–1 and showed peak profile characteristics corresponding to the -OH group, -CH₂ and C-O-C group at wavelengths of 3375 cm^-1, 2875 cm^-1 and 1100 cm^-1 respectively. The microscopic evaluation allowed us to observe the nanofibrillar character of its structure and calculate the diameter of nanofibers, which was around 40-120 nm. Hydrolysis using sulfuric acid and subsequent washing and sonication resulted in obtaining nanoparticles that were combined with the prebiotic polysaccharide kefiran in a 1:10 ratio to obtain cryogels. The viscoelastic characteristics were evaluated and it was observed that the loss tangent was 0,05 at 1 Hz. These cryogels have potential for the development of functional foods.